That's what service shops do for you. They take on the risk that if they order the wrong part, they set it right.
In our shop the test to see if it's the screen is to fit a new screen. Some of your newer technicians do ask if there's another way.
The screen on my satellite L675D quit working. It had not gone anywhere recently, just sitting on my desk so not dropped or anything like that. I hooked up an external monitor and it displays correctly. Anyone know how to test if it is the screen, or transformer? I would hate to order a new screen and have it still not work